In radio communications, a plurality of transport blocks may be bundled together when transmitted, such that a single HARQ process is used for the bundled transport blocks, instead of using a separate HARQ process for each transport block.
Multiple-input and multiple-output (MIMO) is the use of multiple antennas at both the transmitter and receiver to improve communication performance.
R1-111763 “4-branch MIMO for HSDPA”, 3GPP TSG RAN WG1 Meeting #65, Barcelona, Spain, 9-13 May, 2011, proposes introducing a 4-branch MIMO for downlink HSDPA.
At RAN#53, a new work item on 4-branch MIMO transmission for HSDPA was agreed. At RAN#67, it was decided to use 2-codeword MIMO to reduce the control channel design.
R1-120356 “Data Bundling in a 2 codeword MIMO System”, 3GPP TSG-RAN WG1 #68, Dresden, Germany, 6-10 Feb. 2012, discusses different options for bundling at the transmission side when using a 2 code word 4-branch MIMO. Bundling may be done at the bit level or at the symbol level.
Time-division multiplexing (TDM) is a type of multiplexing in which two or more bit streams or signals are transferred apparently simultaneously as sub-channels in one communication channel, but are physically taking turns on the channel over time. The time domain is divided into several recurrent time slots of fixed length, one for each sub-channel. Time-Division Duplex (TDD) is the application of time-division multiplexing to separate uplink (UL) and downlink (DL) signals.